Pencil



T. H. DUNNE June 11, 1929.

PENCIL Filed Oct. 20, 1926 mvENToR MTORNEY Patented `lune 11, 1929.

UNITED STATES THOMAS H. DUNNE, 0F SAN FRANCISCO, CALIFORNIA.

PENCIL.

Application filed October 20, 1926. Serial No. 142,853.

This invention relates to improvements in pencils and more particularly to writing or marking pencils having replaceable leads adapted to be mechanically extended beyond the body of the pencil. Among the objects of this invention are to produce a pencil of this character having the minimum number of parts in combination to produce the desired mechanical effect, with an attractive finish, well balanced, simple in operation and that may be produced at such a low cost that it is adaptable for free distribution for advertising purposes, and as an economical substitute for the conventional Wood pencil having fixed leads therein.

This conventional type of pencil having a lead fixed within a wooden body, While low in first cost, is relatively expensive in ultimate consumption, for the reason that the wooden body is cut away to expose the lead or marking element embedded therein, which is wasteful of the lead because more of it is sharpened away than is actually used for Writing, in many instances. Further waste is due to the fact that when the pencil becomes too short for comfortable writing it is discarded, often amounting to a waste of over fifty per cent. The low productioncost otl the present invention provides for the replacement of the leads or .marking elements they are worn away without wast-ing or destroying the holding element or body of the pencil. The durability of the present structure is sufiicient to outwear so many of the type of pencils having fixed leads, that the cost of the mechanical features of the present invention are more than compensated for.. Practically the entire length of the lead oi writing element is used, and the ultimate quantity that would be consumed within one mechanical holder would represent a. large saving, due to the absence ofV waste of any kind. Other objects and advantages will Aappear as this description progresses.

In this specification and the annexed drawings the invention is illustrated in the form considered the best, but it is to be understood that it is not limited to such form, because it may be embodied in other forms, and it is also to be understood that in and by the claim following the description it is desired to cover the invention in whatsoever form it may be embodied.

In the accompanying one sheet. of draw ings, Figure 1 is a mechanical pencil constructed in accordance with this invention, the enclosing body being shown in longitudinal section and the mechanical combination of elements assembled therein being shown in full line, better to disclose their form and co-operation. Figure 2 is a plan view from above, looking down into the end of the pencil, with the eraser removed, Figure 3 is a fragmentary det-ail partially in cross section, illustrating t-he position of the plunger for ejecting the last stub of lead. Figure 4 is a cross section of a modified form, adapted to tubular metal bodies. For better disclosure the various parts are shown, greatly enlarged, practically twice the normal size.

In detail the construction illustrated in the drawings comprises the tubular shaft or body of the pencil 1, which is preferably made of' wood, paper, or any of the Well known compositions available for this purpose. This body 1 has a central axial bore 2, throughout its length, the lower or Writing end of the body 1 is provided with a sheath 3 tapering to a point and terminating in a central opening, closely fitting the diameter of the lead to be used within the body. This sheath has a parallel portion 4 frictionallyheld on the end of the body 1, that has a. diametrical reduction and is tapered to fit within the sheath so that the body and the sheath will present an externally flush surface. The opposite end of the body is provided Withthe reduced nipple 5 consisting of a tubular section forced onto a diametrical reduction on the end of the body. The tubular ferrule 6 is forced over the nipple 5 and has the same external diameter as the body portion 1 so that it resents a flush surface therewith, the end of the body 1 being diametrically reduced to accomplish this. lVit-h this ferrule 6 placed over the end of the body and the nipple 5, the groove 7 is formed in a swaging machine, which permanently attaches the ferrule 6 to the end of the pencil and the nipple 5; the groove 7 swiveling t-he parts 5 and 6 together and forcing the nipple 5 into the body of the wood, securely assembling the nipple and ferrule on the end of the body 1. The internal and external diameters of the nipple 'and the ferrule 6 are such that the fcrrule 6 swivels freely on the nipple 5, being capable nf n free and #deplete rotation thereon. The ferrule 6 is provided with a knurled portion 8. The act of knurling this portion tends to enlarge the external and internal diameter of the ferrule 6, causing a slight parallel swelling at .this point, with an externallyroughened surface topro vide friction for the fingers in turning the ferrule G. The upper extremity of the ferrule 6 is provided with the thread grooves 9 to aid in frictionally securing the cylindrical rubber eraser 10 therein.

Thelmechanical feed comprises the continuous helix or open spiral 11 formed Vof fiat wire or a ribbon like strip of sheet metal.

'lhel spaced convolutions of the hollow wire when wound upon a mandrel of the desired size, forms in mechanical eiiect, a hollow thread or screw, rotatably fitting `within the parallel axial bore 2throughout the body of` the pencil. The upperend of this helix terminates in an enlarged head integral therelwith,"but wound upon a larger mandrel to form ineffeet a compact expansive head 12. The travellerl for expelling the lead or fmarking element '.fronrthe body, comprises a length of wirelS-bent back upon itself at 14: and again bent back upon itself at 15 and terminating'against the side of stem 13. Thel distance betweennthe bends 14 and 15 is approximately equal to about two convolutions-of the helix 11. This plunger is assembledupon the helix by `holding it in one hand while lthefend 16 of the :helix is rotatedthrough-the loopv formed between the zbends ltand 15, which carries the stem 13 within the-helix, leaving the parallel extension 17 outside the helix.

TheV combination is assembled byi-grasping the head-'12 of the helix and forcing the -end 1G into the upper end of the bore 2 through the body ofthe pencil, the loop 17 of the plungery engaging the longitudinalvr groove-18 formed throughoutthe length of the bore 2. The head `12 is then forced into ,the upper end `of the -ferrule until it exfer-rule, completing the assembly and thez finish. of the body rof the pencil.

lVith the plunger in the retracted position as shownin Figure 1, one or .more lengths of leads such as 19 and 20 are rinserted in the open end of the sheath 3 and areforced upward within the helix 11,

within which they snugly fit,.yet may lon-V gitudinally freely move.y It is desirable that this lead 19 fit snugly' within the helix 11 sothat there will be" nolost` motion or wobblingof the lead during the' .acti kof writing and to prevent the lead sliding out of the'body'of theV pencil. As the point 19 wears away the body 1 of the pencil is grasped in the right hand and the ferrule G turned .to the right or clock-wise, which aauses the 'left hand thread of the helix 11, working within the loop of the traveller 17 to force the same outward, the end of the stem 13 'impinging against the upper end of the lead 2O forces the same forward, which in turn forces the lead 19 forward, exposing more writing element until all of the leads are consumed. By the time the loop 15 impinges against the tapered side of the sheath 3, the end of theplunger 13 has protruded through the endlof the lsheath and ejected the last stub lof lead, see Figure To` relill the pencil the ferrule G is then turned `inthe reverse or contra-clockwise direction which again screws the traveller back into the position shown in Figure 1, ready to receive'a new charge of lead within the magazine formed bythe length of the helix 11. lt is desirable to divide the length of lead as shown, -sincea continuous Y length of approximately five inches ris liable to breakage and is unwieldly for various obvious reasons. A furtheradvantage of the shorter leads within the magazine, is that more than oneY color may be carried.` -For instance,the lead-19 might be black. or blue and the lead -20,.red, or any other contrasted color. It often happensl that lfor checking invoices and other such purposes it is vdesirable to use a set color marking, perhaps over a period of hours at a time, or during another period, it would be desirable to use another color. AAny of the eolorswithin the magazine are available by merely turn` ing the ferrule '6 until the desired 'color is exposed ythrough the end ofthe sheath 3, the ejected lead beingulaidaside Vfor reinsertion.

The body portion 1 being of vwood or similar composition, is susceptible to enamelingpcoloring and other treatment, ren? dering it attractive-to the eye and comfortable to the touch.1 The outer surface may also carrying advertising zmatter imprinted thereon, making this invention an economical, attractive advertising. medium for free distribution.

It is obviousrthatthe body portion 1 may be made of a metal tube, square or polygonal, the loop17 of the plunger travelling up and down in onewof the anglesof the tubeto Aprevent it from turning, serving the same function the grooi'fe 2 in the wooden body portionv 1, see Figure et; This modification -is particularly adaptable to the use of largeanarking crayons, wherein it is desirable to keep the' cross sectional diameter of the body 1 within lcomfortablev size. The particular advantage ofthe structure shown nFgure l` is that,.leads vofirel'ativelgi7 .large diameter may be inserted Within the convventional diameter of the ordinary wooden peneil, which is approximately five-sixteenths of an inch. This structure also lends itself to the making of pencils of very small diameter for handling small leads for insertion Within pocket memorandum books7 or purses.

Having thus described this `invention what I claim and desire to secure by Letters Patent is:

A mechanical pencil Comprising a body having a longitudinal bore with a groove extending laterally therefrom throughout the length of said body; a nipple surrounding the end of said body and attached thereto by a depressed groove; a ferrule surrounding said nipple and engaged to swivel in said groove; a tapered sheath on the end of said body flush with the outer surface thereof and terminating in an opening co-axial with said bore; a helix Within said bore and extending beyond both ends Y of said body and having an enlarged spiral head expansively and directly engaging within said ferrule and adapted to be driven thereby, the opposite end of said helix extending Within said sheath to near said opening therein; and a traveler looped into and driven by said helix and guided in said lateral groove in the body and adapted to advance beyond the end of said sheath a lead held Within and by said helix.

In testimony whereof I have hereunto affixed my signature.

THOMAS H. DUNNE. 

